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/*
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 * Copyright (c) 2012, Stephen Colebourne & Michael Nascimento Santos
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  * Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 *  * Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
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 *  * Neither the name of JSR-310 nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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package java.time.temporal;

import java.time.DateTimeException;
import java.time.chrono.Chronology;
import java.time.format.ResolverStyle;
import java.util.Locale;
import java.util.Map;
import java.util.Objects;

/**
 * A field of date-time, such as month-of-year or hour-of-minute.
 * <p>
 * Date and time is expressed using fields which partition the time-line into something
 * meaningful for humans. Implementations of this interface represent those fields.
 * <p>
 * The most commonly used units are defined in {@link ChronoField}.
 * Further fields are supplied in {@link IsoFields}, {@link WeekFields} and {@link JulianFields}.
 * Fields can also be written by application code by implementing this interface.
 * <p>
 * The field works using double dispatch. Client code calls methods on a date-time like
 * {@code LocalDateTime} which check if the field is a {@code ChronoField}.
 * If it is, then the date-time must handle it.
 * Otherwise, the method call is re-dispatched to the matching method in this interface.
 *
 * @implSpec This interface must be implemented with care to ensure other classes operate correctly.
 * All implementations that can be instantiated must be final, immutable and thread-safe.
 * Implementations should be {@code Serializable} where possible. An enum is as effective
 * implementation choice.
 * @since 1.8
 */
public interface TemporalField {

  /**
   * Gets the display name for the field in the requested locale.
   * <p>
   * If there is no display name for the locale then a suitable default must be returned.
   * <p>
   * The default implementation must check the locale is not null
   * and return {@code toString()}.
   *
   * @param locale the locale to use, not null
   * @return the display name for the locale or a suitable default, not null
   */
  default String getDisplayName(Locale locale) {
    Objects.requireNonNull(locale, "locale");
    return toString();
  }

  /**
   * Gets the unit that the field is measured in.
   * <p>
   * The unit of the field is the period that varies within the range.
   * For example, in the field 'MonthOfYear', the unit is 'Months'.
   * See also {@link #getRangeUnit()}.
   *
   * @return the unit defining the base unit of the field, not null
   */
  TemporalUnit getBaseUnit();

  /**
   * Gets the range that the field is bound by.
   * <p>
   * The range of the field is the period that the field varies within.
   * For example, in the field 'MonthOfYear', the range is 'Years'.
   * See also {@link #getBaseUnit()}.
   * <p>
   * The range is never null. For example, the 'Year' field is shorthand for
   * 'YearOfForever'. It therefore has a unit of 'Years' and a range of 'Forever'.
   *
   * @return the unit defining the range of the field, not null
   */
  TemporalUnit getRangeUnit();

  /**
   * Gets the range of valid values for the field.
   * <p>
   * All fields can be expressed as a {@code long} integer.
   * This method returns an object that describes the valid range for that value.
   * This method is generally only applicable to the ISO-8601 calendar system.
   * <p>
   * Note that the result only describes the minimum and maximum valid values
   * and it is important not to read too much into them. For example, there
   * could be values within the range that are invalid for the field.
   *
   * @return the range of valid values for the field, not null
   */
  ValueRange range();

  //-----------------------------------------------------------------------

  /**
   * Checks if this field represents a component of a date.
   * <p>
   * A field is date-based if it can be derived from
   * {@link ChronoField#EPOCH_DAY EPOCH_DAY}.
   * Note that it is valid for both {@code isDateBased()} and {@code isTimeBased()}
   * to return false, such as when representing a field like minute-of-week.
   *
   * @return true if this field is a component of a date
   */
  boolean isDateBased();

  /**
   * Checks if this field represents a component of a time.
   * <p>
   * A field is time-based if it can be derived from
   * {@link ChronoField#NANO_OF_DAY NANO_OF_DAY}.
   * Note that it is valid for both {@code isDateBased()} and {@code isTimeBased()}
   * to return false, such as when representing a field like minute-of-week.
   *
   * @return true if this field is a component of a time
   */
  boolean isTimeBased();

  //-----------------------------------------------------------------------

  /**
   * Checks if this field is supported by the temporal object.
   * <p>
   * This determines whether the temporal accessor supports this field.
   * If this returns false, then the temporal cannot be queried for this field.
   * <p>
   * There are two equivalent ways of using this method.
   * The first is to invoke this method directly.
   * The second is to use {@link TemporalAccessor#isSupported(TemporalField)}:
   * <pre>
   *   // these two lines are equivalent, but the second approach is recommended
   *   temporal = thisField.isSupportedBy(temporal);
   *   temporal = temporal.isSupported(thisField);
   * </pre>
   * It is recommended to use the second approach, {@code isSupported(TemporalField)},
   * as it is a lot clearer to read in code.
   * <p>
   * Implementations should determine whether they are supported using the fields
   * available in {@link ChronoField}.
   *
   * @param temporal the temporal object to query, not null
   * @return true if the date-time can be queried for this field, false if not
   */
  boolean isSupportedBy(TemporalAccessor temporal);

  /**
   * Get the range of valid values for this field using the temporal object to
   * refine the result.
   * <p>
   * This uses the temporal object to find the range of valid values for the field.
   * This is similar to {@link #range()}, however this method refines the result
   * using the temporal. For example, if the field is {@code DAY_OF_MONTH} the
   * {@code range} method is not accurate as there are four possible month lengths,
   * 28, 29, 30 and 31 days. Using this method with a date allows the range to be
   * accurate, returning just one of those four options.
   * <p>
   * There are two equivalent ways of using this method.
   * The first is to invoke this method directly.
   * The second is to use {@link TemporalAccessor#range(TemporalField)}:
   * <pre>
   *   // these two lines are equivalent, but the second approach is recommended
   *   temporal = thisField.rangeRefinedBy(temporal);
   *   temporal = temporal.range(thisField);
   * </pre>
   * It is recommended to use the second approach, {@code range(TemporalField)},
   * as it is a lot clearer to read in code.
   * <p>
   * Implementations should perform any queries or calculations using the fields
   * available in {@link ChronoField}.
   * If the field is not supported an {@code UnsupportedTemporalTypeException} must be thrown.
   *
   * @param temporal the temporal object used to refine the result, not null
   * @return the range of valid values for this field, not null
   * @throws DateTimeException if the range for the field cannot be obtained
   * @throws UnsupportedTemporalTypeException if the field is not supported by the temporal
   */
  ValueRange rangeRefinedBy(TemporalAccessor temporal);

  /**
   * Gets the value of this field from the specified temporal object.
   * <p>
   * This queries the temporal object for the value of this field.
   * <p>
   * There are two equivalent ways of using this method.
   * The first is to invoke this method directly.
   * The second is to use {@link TemporalAccessor#getLong(TemporalField)}
   * (or {@link TemporalAccessor#get(TemporalField)}):
   * <pre>
   *   // these two lines are equivalent, but the second approach is recommended
   *   temporal = thisField.getFrom(temporal);
   *   temporal = temporal.getLong(thisField);
   * </pre>
   * It is recommended to use the second approach, {@code getLong(TemporalField)},
   * as it is a lot clearer to read in code.
   * <p>
   * Implementations should perform any queries or calculations using the fields
   * available in {@link ChronoField}.
   * If the field is not supported an {@code UnsupportedTemporalTypeException} must be thrown.
   *
   * @param temporal the temporal object to query, not null
   * @return the value of this field, not null
   * @throws DateTimeException if a value for the field cannot be obtained
   * @throws UnsupportedTemporalTypeException if the field is not supported by the temporal
   * @throws ArithmeticException if numeric overflow occurs
   */
  long getFrom(TemporalAccessor temporal);

  /**
   * Returns a copy of the specified temporal object with the value of this field set.
   * <p>
   * This returns a new temporal object based on the specified one with the value for
   * this field changed. For example, on a {@code LocalDate}, this could be used to
   * set the year, month or day-of-month.
   * The returned object has the same observable type as the specified object.
   * <p>
   * In some cases, changing a field is not fully defined. For example, if the target object is
   * a date representing the 31st January, then changing the month to February would be unclear.
   * In cases like this, the implementation is responsible for resolving the result.
   * Typically it will choose the previous valid date, which would be the last valid
   * day of February in this example.
   * <p>
   * There are two equivalent ways of using this method.
   * The first is to invoke this method directly.
   * The second is to use {@link Temporal#with(TemporalField, long)}:
   * <pre>
   *   // these two lines are equivalent, but the second approach is recommended
   *   temporal = thisField.adjustInto(temporal);
   *   temporal = temporal.with(thisField);
   * </pre>
   * It is recommended to use the second approach, {@code with(TemporalField)},
   * as it is a lot clearer to read in code.
   * <p>
   * Implementations should perform any queries or calculations using the fields
   * available in {@link ChronoField}.
   * If the field is not supported an {@code UnsupportedTemporalTypeException} must be thrown.
   * <p>
   * Implementations must not alter the specified temporal object.
   * Instead, an adjusted copy of the original must be returned.
   * This provides equivalent, safe behavior for immutable and mutable implementations.
   *
   * @param <R> the type of the Temporal object
   * @param temporal the temporal object to adjust, not null
   * @param newValue the new value of the field
   * @return the adjusted temporal object, not null
   * @throws DateTimeException if the field cannot be set
   * @throws UnsupportedTemporalTypeException if the field is not supported by the temporal
   * @throws ArithmeticException if numeric overflow occurs
   */
  <R extends Temporal> R adjustInto(R temporal, long newValue);

  /**
   * Resolves this field to provide a simpler alternative or a date.
   * <p>
   * This method is invoked during the resolve phase of parsing.
   * It is designed to allow application defined fields to be simplified into
   * more standard fields, such as those on {@code ChronoField}, or into a date.
   * <p>
   * Applications should not normally invoke this method directly.
   *
   * @param fieldValues the map of fields to values, which can be updated, not null
   * @param partialTemporal the partially complete temporal to query for zone and chronology;
   * querying for other things is undefined and not recommended, not null
   * @param resolverStyle the requested type of resolve, not null
   * @return the resolved temporal object; null if resolving only changed the map, or no resolve
   * occurred
   * @throws ArithmeticException if numeric overflow occurs
   * @throws DateTimeException if resolving results in an error. This must not be thrown by querying
   * a field on the temporal without first checking if it is supported
   * @implSpec If an implementation represents a field that can be simplified, or combined with
   * others, then this method must be implemented. <p> The specified map contains the current state
   * of the parse. The map is mutable and must be mutated to resolve the field and any related
   * fields. This method will only be invoked during parsing if the map contains this field, and
   * implementations should therefore assume this field is present. <p> Resolving a field will
   * consist of looking at the value of this field, and potentially other fields, and either
   * updating the map with a simpler value, such as a {@code ChronoField}, or returning a complete
   * {@code ChronoLocalDate}. If a resolve is successful, the code must remove all the fields that
   * were resolved from the map, including this field. <p> For example, the {@code IsoFields} class
   * contains the quarter-of-year and day-of-quarter fields. The implementation of this method in
   * that class resolves the two fields plus the {@link ChronoField#YEAR YEAR} into a complete
   * {@code LocalDate}. The resolve method will remove all three fields from the map before
   * returning the {@code LocalDate}. <p> A partially complete temporal is used to allow the
   * chronology and zone to be queried. In general, only the chronology will be needed. Querying
   * items other than the zone or chronology is undefined and must not be relied on. The behavior of
   * other methods such as {@code get}, {@code getLong}, {@code range} and {@code isSupported} is
   * unpredictable and the results undefined. <p> If resolution should be possible, but the data is
   * invalid, the resolver style should be used to determine an appropriate level of leniency, which
   * may require throwing a {@code DateTimeException} or {@code ArithmeticException}. If no
   * resolution is possible, the resolve method must return null. <p> When resolving time fields,
   * the map will be altered and null returned. When resolving date fields, the date is normally
   * returned from the method, with the map altered to remove the resolved fields. However, it would
   * also be acceptable for the date fields to be resolved into other {@code ChronoField} instances
   * that can produce a date, such as {@code EPOCH_DAY}. <p> Not all {@code TemporalAccessor}
   * implementations are accepted as return values. Implementations that call this method must
   * accept {@code ChronoLocalDate}, {@code ChronoLocalDateTime}, {@code ChronoZonedDateTime} and
   * {@code LocalTime}. <p> The default implementation must return null.
   */
  default TemporalAccessor resolve(
      Map<TemporalField, Long> fieldValues,
      TemporalAccessor partialTemporal,
      ResolverStyle resolverStyle) {
    return null;
  }

  /**
   * Gets a descriptive name for the field.
   * <p>
   * The should be of the format 'BaseOfRange', such as 'MonthOfYear',
   * unless the field has a range of {@code FOREVER}, when only
   * the base unit is mentioned, such as 'Year' or 'Era'.
   *
   * @return the name of the field, not null
   */
  @Override
  String toString();


}
